Tool clamping device

ABSTRACT

The invention relates to a tool clamping device, with a spindle insert ( 10 ) and an adapter ( 12 ) between the spindle insert ( 10 ) and a toolholder ( 14 ), and the adapter ( 12 ) can be pushed axially to the longitudinal axis ( 16 ) of the device into the holder ( 18 ) of the spindle insert ( 10 ) and can be fixed by a fastening means ( 20 ). Because in addition to the fastening means ( 20 ), between the spindle insert ( 10 ) and adapter ( 12 ) there is a torque transmission means ( 22 ) which establishes a positive connection between the spindle insert ( 10 ) and adapter ( 12 ), in this way the actual fastening means is relieved of stresses and loads.

The invention relates to a tool clamping device, with a spindle insert and an adapter between the spindle insert and a toolholder, and the adapter can be pushed axially to the longitudinal axis of the device into the holder of the spindle insert and can be fixed by fastening means.

DE 102 19 600 B4 discloses a tool carrier for stationary or rotating tools with a collet holder made on the tool carrier means for a collet for clamping the tool shaft from the tool side, the collet holder having a conical hole for holding the collet and a coaxial thread assigned to the hole for holding the clamping nut, with a precision finish-machined first flat surface, which is assigned to a conical hole, and which runs at a right angle to the axis of the hole, on the tool carrier means, and with fastening means on the tool carrier means for a tool clamping insert which is inserted into the conical hole with a conical holding pin instead of a collet, the fastening means being accessible exclusively from the tool side.

The known solution results in a tool carrier with an axially very short collet holder which is designed so that in an extremely small area also other tool holders such as a collet can be used. For the actual tool clamping process, in the known solution, in addition to the spindle insert and the adapter, there is a clamping nut for the tool which can be fixed with the fastening means from the tool side, so that a corresponding diversity of parts is necessary for implementing the known solution.

DE 299 13 650 U1 discloses a generic tool clamping device, with a spindle insert and an adapter between the spindle insert and the toolholder, and the adapter can be pushed axially into the spindle insert and can be attached to it by at least one screw as the fastening means. The adapter in its front area has at least one groove which runs in the longitudinal direction and which on its end discharges into a recess running transversely to it and can be inserted into the spindle insert by means of the adapter via at least one screw tip of the fastening means, which tip projects into the interior of the spindle insert. By subsequent twisting of the adapter the screw tip of the fastening means projects into the recess and in this way secures the adapter against falling out of the spindle insert. In this known generic solution the adapter is held solely in the spindle insert via the contact forces of the respective screw fastening means; on this one hand, this leads in the axial direction to a corresponding large tool clamping device, and on the other, especially for impact-like application of force to the machining tool with application of a high torque to the adapter with the tool, unwanted relative motion between the adapter and tool insert is possible in the form of a slipping or sliding process which releases the connection.

On the basis of this prior art, the object of the invention is to further improve the known solutions while retaining their advantages such that not only in the axial direction of the tool clamping device is a low axial overall length attainable, but also that even for machining with a highly loaded tool, secure fixing between the tool adapter and spindle insert is achieved. This object is achieved by a tool clamping device with the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, in addition to the fastening means for fixing the adapter in the spindle insert between the spindle insert and adapter, there is a torque transmission means which establishes a positive connection between the spindle insert and adapter, the actual fastening means is relieved of stresses and loads which occur especially to a considerable degree when impact-like application of machining forces to the tool and/or in machining processes with high torque transmissions causes a departure from the range of conventional cutting forces. Due to the separate torque transmission means, the fastening means is relieved such that in any case it can securely fix the adapter in the spindle insert during metal cutting with the tool. It is surprising to one skilled in the art in the field of cutting that in spite of providing a separate torque transmission means for the actual fastening means, installation space can be saved so that the solution as claimed in the invention is dimensioned to be correspondingly small in the axial direction, to which also contributes the fact that no separate parts such as for example a clamping nut are necessary to achieve secure fixing of the machining chain consisting of the cutting tool, adapter and spindle insert.

In one especially preferred embodiment of the tool clamping device as claimed in the invention, it is provided that the actual machining tool is fixed in the tool holder by way of another fastening means, preferably by means of a screw. This fastening means engages a flat recess in the cylindrical shaft of the machining tool, and with the torque transmission means as claimed in the invention it is ensured that this fastening site is secured such that unintentional slippage of the tool in the tool holder of the adapter at the location of engagement of the fastening means is reliably avoided. If in another preferred embodiment one fastening means in the form of a fastening screw enables oblique engagement by the spindle insert, in this way, set obliquely, a tightening moment for the adapter in the direction of the base of the spindle insert can be achieved. In particular, when the adapter has a conical holding piece on its free end, as a result a reliable, play-free fixing possibility is achieved.

Other advantageous embodiments of the tool clamping device as claimed in the invention are the subject matter of the other dependent claims.

The tool clamping device as claimed in the invention will be detailed below using two embodiments as shown in the drawings. The figures are schematic and not to scale.

FIG. 1 shows in a perspective view partially cutaway the tool clamping device,

FIGS. 2 and 3 shows the tool clamping device as shown in FIG. 1 in different longitudinal sections,

FIGS. 4 a, 4 b two different embodiments of the torque transmission means, both the back view of the adapter as shown in FIGS. 1 to 3 and a front view of the spindle insert for a correspondingly modified embodiment.

The tool clamping device shown in FIG. 1 has a spindle insert 10 and an adapter 12. The already addressed adapter 12 extends between the spindle insert 10 and a tool holder 14. The adapter 12 can be reversibly inserted in a holder 18 of the spindle insert 10 axially to the longitudinal direction 16 of the device. Furthermore the adapter 12 in the spindle insert 10 can be fixed by way of a fastening means designated as a whole as 20. In addition to the aforementioned fastening means 20, between the spindle insert 10 and the adapter 12 there is a torque transmission means designated as a whole as 22 which produces a positive connection between the spindle insert 10 and the adapter 12. As shown in FIG. 1, on the front sides 24, 26 of the two parts facing one another, formed from the spindle insert 10 and adapter 12, there is at least one projection 28 on one part, here in the form of a spindle insert 10 which positively engages a corresponding recess 30 in the other part, here in the form of the adapter 12, with formation of the torque transmission means 22.

For the sake of simpler representation, the front sides 24, 26 are shown with formation of a gap at a distance; in the actual implementation this gap distance can be set to zero. The indicated projection 28 consist of a block-like material projection on the front side 26 of the spindle insert 10. Instead of a single projection 28, in a modified embodiment as shown in FIG. 4 b it can be repeatedly present on the front-side outer periphery of the spindle insert 10. Thus, for example the embodiment illustrated in FIG. 4 b shows two projections 28 a,b diametrically opposite one another to the longitudinal axis 16. In this case, then two corresponding recesses (not shown) on the other part are necessary. As in the illustrated embodiments, it is of course possible to assign a projection to the adapter 12 or the spindle insert 10 in an alternating sequence. Likewise it is still within the scope of the invention to configure the respective projection 28 on the front side 24 of the adapter 12. But in order to achieve reliable relief of the first fastening means 20, in any case the illustrated torque transmission means 22 should be located at a location different therefrom in the tool clamping device.

Furthermore the spindle insert 10 on its one free front side 26 has a step-shaped shoulder 32 which is used to extend over the annular flange segment 34 of the adapter 12. In the first embodiment as illustrated in FIGS. 1 and 4 a, as already shown only one rectangular projection 28 extends into the assignable recess 30 of the adapter 12. In the embodiment as shown in FIG. 4 b, however provision is made such that the respective projections 28 a, b of the torque transmission means 22 are interconnected via connecting bridges 36 which extend in the form of arcs to the exterior, oriented around the longitudinal axis 16 of the device. In particular, as shown in FIG. 4 b, there are two projections 28 a,b which extend diametrically opposite one another to the longitudinal axis 16 of the device, and preferably likewise extend opposite the arc-shaped connecting bridges 36. As furthermore is to be seen in FIG. 4 b, outside the two connecting bridges 36 with formation of a step-shaped shoulder 32, the spindle insert (10) is cut free and furthermore has these flat bearing surfaces 38 for the action of an actuating tool, for example in the form of an actuating wrench with a definable jaw width (not shown).

As furthermore follows from FIG. 3, the fastening means 20 consists of two fastening screws 40 which are opposite diametrically to the longitudinal axis 16; the screw-in direction for the two fastening screws 40 is selected to be oblique to the longitudinal axis 16 of the device, such that the conical end piece 42 of the adapter 12 is pulled into the holder 18 of the spindle insert 10 upon completed fixing. So that the end of the respective fastening screw 40 can act on the adapter 12 as required, it is provided at least in regions or segments on one end of the conical end piece 42 with an annular shoulder 44 which widens in diameter. Proceeding from the annular shoulder 44, the adapter 12 widens in turn to the exterior and in this way forms a holding ring 46 which encompasses the tool shaft 48 of an actuating tool in the area of its free end. To fix the machining tool 50 in the tool holder 14 of the adapter 12, in turn another fastening means 52 is used in the form of a fastening screw. This fixing situation for the tool 50 is shown especially in FIG. 2. For the action of the other fastening means 52 in the form of a screw, the tool 50 is provided on its cylindrical tool shaft 48 with a groove-like recess 54 with a groove base which runs flat. One fastening means 20 therefore extends through the spindle insert 10 and acts on the adapter 12 to fix it, the other fixing means 52 extending through the adapter 12 and acting on the tool 50 to fix it. Due to the relief by the positive locking of the torque transmission means 22, it is ensured in this respect for the other fixing means 52 that it cannot slide out of the recess 54; this could obviate the necessity of fixing the machining tool 50 in the adapter 12 and therefore in the spindle insert 10.

The tool clamping device as claimed in the invention is small in the axial direction, securely fixes the machining tool 50 with the adapter 12 in the spindle insert 10, and prevents damaging relative movements between the indicated parts, and possibly failure of the individual fastening means 20 and 52. Within the conical end piece 42 of the adapter 12 a stop piece 56 is held by means of a thread, with which piece it is possible to fix the possible insertion depth for the tool 50 along the longitudinal axis 16 of the device by a length setting process. In addition to the drilling tool 50 shown in the figures, for example a milling cutter, an inside piercing tool and the like can be held in the illustrated holder configuration. Furthermore, the respective tool 50 when worn can be replaced by a new one. If the spindle insert 10 is a component of a spindle head which is not shown, this configuration, preferably in so-called turret-type tool heads, especially turret-type disks, can be used. Moreover it is possible to hold the spindle insert 10 stationary and to drive the workpiece which is not shown, for example for drilling or turning via a machine turning attachment which is not shown, or with the workpiece held stationary, to drive the spindle insert, for example via a rotary tool holder (not shown) for a cutting process. Likewise, in special cases, by relative movement to one another both the tool and also the workpiece can be driven. Furthermore, the solution as claimed in the invention is not limited to the adapter 12 with conically running end pieces 42; rather here tool designs are also conceivable in which the end piece is made cylindrical (not shown) 

1. A tool clamping device, with a spindle insert (10) and an adapter (12) between the spindle insert (10) and a toolholder (14), and the adapter (12) can be pushed axially to the longitudinal axis (16) of the device into the holder (18) of the spindle insert (10) and can be fixed by a fastening means (20), characterized in that in addition to the fastening means (20), between the spindle insert (10) and adapter (12) there is a torque transmission means (22) which establishes a positive connection between the spindle insert (10) and adapter (12).
 2. The tool clamping device as claimed in claim 1, wherein on the front sides (24, 26) of the parts spindle insert 10 and adapter 12, which sides face one another, there is at least one projection (28) on one part which engages a corresponding recess (30) in the other part, with formation of the torque transmission means (22).
 3. The tool clamping device as claimed in claim 2, wherein the spindle insert (10) on its one free front side (26) has the respective projection (28) and a step-shaped shoulder (32) which is used to extend over the annular flange segment (34) of the adapter (12).
 4. The tool clamping device as claimed in one of claims 1 to 3, wherein the respective projections (28 a, b) of the torque transmission means (22) are interconnected via connecting bridges (36) which extend in the form of arcs around the longitudinal axis (16) of the device.
 5. The tool clamping device as claimed in claim 4, wherein there are two projections (28 a,b) which extend diametrically opposite one another to the longitudinal axis (16), and between which the arc-shaped connecting bridges (36) extend opposite one another.
 6. The tool clamping device as claimed in one of claims 4 or 5, wherein outside the connecting bridges (36) with formation of a step-shaped shoulder (32) the spindle insert (10) is cut free and has flat bearing surfaces (38) for the action of an actuating tool.
 7. The tool clamping device as claimed in one of claims 1 to 6, wherein one fastening means (20) consists of two fastening screws (40) which are opposite diametrically to the longitudinal axis (16), with a screw-in direction which runs obliquely to the longitudinal axis (16) such that the conical end piece (42) of the adapter (12) is pulled into the holder (18) of the spindle insert (10) over the annular shoulder (44) of the adapter (12).
 8. The tool clamping device as claimed in one of claims 1 to 7, wherein another fastening means (52) is used to fix the tool (50) in the tool holder (14) of the adapter (12).
 9. The tool clamping device as claimed in claim 8, wherein the tool (50) on its cylindrical shaft (48) is provided with a recess (54) for the action of another fastening means (52), preferably in the form of an individual screw.
 10. The tool clamping device as claimed in claim 8 or 9, wherein one fastening means (20) extends through the spindle insert (10) and acts on the adapter (12) to fix it and wherein the other fixing means (52) extending through the adapter (12) acts on the tool (50) to fix it. 